Acoustic measurements are an important tool in measuring properties of various media, such as the composition of earth formations. For example, measurements of the speed of acoustic waves through formations allows for the estimation of properties such as the types and amounts of materials making up a formation, and formation porosity.
Acoustic transmitters typically include an actuator configured to perform an oscillating motion. This oscillating motion is transferred to an acoustic diaphragm that in turn generates acoustic waves. Such transmitters typically include a direct coupling mechanism between the actuator and the diaphragm. Typical piezoelectric acoustic transmitters include a piezoelectric actuator directly attached to an interior of an acoustic diaphragm within an acoustic chamber. These transmitters generally include an oil-filled acoustic chamber formed with the actuator and the diaphragm. Such transmitters are generally limited in their output bandwidth, particularly at lower frequencies.